1. Field of the Invention
The present invention relates to preparation of polychlorinated pyridine mixtures by direct liquid phase chlorination of beta-picoline or beta-picoline hydrochloride. Typical of the products produced are 2,3,6-trichloro- and 2,3,5,6-tetrachloro pyridine; and 3-chloro-, 5-chloro-, 6-chloro-, 2,6-dichloro-, 5,6-dichloro- and 2,5,6-trichloro-3-trichloromethyl pyridine. These products have utility, for example, as intermediates for herbicides and insecticides. A further aspect of the present invention relates to further non-catalytic chlorination of mixtures rich in 2-chloro-and 6-chloro-3-trichloromethyl pyridine to form 2,6-dichloro-3-trichloromethyl pyridine and/or 2,3,6-trichloro pyridine, and the further non-catalytic chlorination of mixtures rich in 5-chloro-3-trichloromethyl pyridine and 5,6-dichloro-3-trichloromethyl pyridine to form 2,5,6-trichloro-3-trichloromethyl pyridine and/or 2,3,5,6-tetrachloro pyridine.
Yet another aspect of the invention relates to catalytically chlorinating mixtures rich in 6-chloro- and mixtures rich in 2,6-dichloro-3-trichloromethyl pyridine to form mixtures rich in 5,6-dichloro- and 2,5,6-trichloro-3-trichloromethyl pyridine. The mixtures rich in 5,6-dichloro- and 2,5,6-trichloro-3-trichloromethyl pyridine may then be non-catalytically chlorinated to form mixtures rich in 2,3,5,6-tetrachloro pyridine.
Still another aspect relates to the formation of 2,3,5,6-tetrachloro pyridine from both catalytic and non-catalytic chlorination of 2,3,6-trichloro pyridine.